Schiit Bifrost / Bifrost Uber

Hardware Review

Schiit Bifrost / Bifrost Uber

Thursday, August 7, 2014

DAC

Richard Barclay

California-based Schiit Audio was established in June 2010 by industry stalwarts Mike Moffat - digital audio specialist and founder of Theta - and Jason Stoddard - former chief amplification engineer at Sumo. Their ambitious mission was to bring high-end performance and superior design and build quality to audio products, manufactured locally in the USA, and sell at “Chinese prices”. A little over one year later in September 2011, the duo introduced the Bifrost, the first DAC to be added to their fledgling but already well-received product range of headphone amplifiers. The release was accompanied by bold statements of intent from the co-founders. Claims that they were “changing the level of entry-level”, that “low cost shouldn’t be an excuse for a throwaway product”, and that the Bifrost was “the world’s most affordable fully upgradable DAC”, certainly had desired effect of grabbing the attention of the digital audio community.

My being in the market for a new standalone DAC was therefore very timely. The Bifrost was a recurring recommendation and appeared to be the converter that met my requirements the best. Luckily - and around the same time - Mark Dolbear of Electromod became the exclusive UK retailer of Schiit Audio products. After a friendly chat and £20 deposit I had a USB-equipped Bifrost sent to me on a fortnight’s trial. It impressed me enough during the evaluation period that I committed to purchasing one in April 2012. Schiit’s Uber upgrade was made available in April 2013, just over 18 months after the initial release of the Bifrost. (As I will explain in the section after next, the Bifrost Uber is a Bifrost with an upgraded analogue output stage.) Glowing reviews were quick to spread across the forums, and inevitably I could not resist the opportunity to hear for myself what the latest excitement was about. After another friendly chinwag with Mark, I soon had a USB-equipped Bifrost Uber loaner in my possession and - suitably impressed with the improvement - my decision to upgrade to the Uber in May 2014 was not as difficult as I had anticipated.

Dim the lightsLike all Schiit Audio products, the Bifrost offers exceptional build quality for the price. Consistent with the rest of the range, a single sheet of sturdy 3mm machined aluminium in brushed satin finish curves around a steel inner chassis to form the face, top and underside of the unit. Tipping the scales at 5 lbs, the Bifrost is also reassuringly weighty for its nine inch width, a footprint shared by Schiit’s Asgard, Valhalla and Lyr - which permits neat stacking if you own one of the aforementioned headphone amplifiers and wish to use the Bifrost as its source. While this DAC may have been aesthetically styled to match these headphone amps, it would be wrong to restrict it to the niche of headphone audio. As a DAC it is equally adept in a main or headphone system or indeed - as I have found - both simultaneously!

Like the amps, the top surface displays the Schiit Audio brand logo to the left and a punched grid array of ventilation holes to the right, although on this DAC the ‘holes’ are faux; they do not serve to vent the internal components but are included to maintain aesthetic consistency. A second and smaller brand logo accompanies ‘Bifrost’, which is printed in a subtle but stylish typeface on the front of the unit. The front features a single, circular and flat push button that is used to toggle between the three inputs. The inputs are denoted by subtle graphics that are in keeping with the unit’s understated and minimalist design - one that is carried across the entire Schiit range - and three white LEDs are used to indicate which input is engaged. The main criticism I have with the styling is Schiit’s decision to follow the current trend of installing garishly bright LEDs into their products. Their dazzling intensity jars with the otherwise subtle design and is far from conducive to the creation of a relaxing mood, particularly in a dimly-lit room and especially if the unit is seated at eye-level. After persevering for a few days I relinquished and bought a pack of silver LightDims (sunglasses for LEDs), which lessen the brightness of the diodes in an unobtrusive way that is easily undoable. Those with a keen eye will also notice the absence of an on/off switch on the front of the unit. An elegantly simple and functional metal toggle switch is instead located to the rear. While I can fully appreciate the designers’ desire to maintain streamlined and minimalistic fascias across their product range, the absence of a front-mounted power switch does make this daily activity a bit of a chore if you have your DAC positioned in a way that makes rear access difficult. According to its creators however, the Bifrost is content to be kept in a powered-on state continuously, as it maintains only a lukewarm temperature and draws a mere 12 watts. For the planet- and penny-conscious however, it still makes sense to power the unit down during prolonged periods of inactivity.

Upgradable affordabilityThe Bifrost and Bifrost Uber are identical in all features, connectivity and specification with the exception of the analogue output stage. Both models use the state-of-the-art (at time of writing!) AKM4399 32-bit D/A converter, boast a sophisticated bit-perfect clock management system, and employ fully discrete low noise JFET analogue sections. What elevates a standard Bifrost to ‘Uber’ status is the superior analogue stage found in the more advanced and expensive Gungnir DAC. With a more sophisticated topology and DC servo to eliminate capacitors in the signal path, this upgrade not only improves measured but also - the designers claim - sonic performance. Unlike the Gungnir which - in addition to its stereo pair of balanced XLR analogue outputs - is unusually but very conveniently lavished with two stereo pairs of 2.0Vrms single-ended RCA analogue outputs, the Bifrost and Bifrost Uber are solely single-ended and equipped with just one pair of outputs. It is however easy enough to use RCA splitters to fork the output signal to two amplifiers if desired, without a suffering a reduction in quality.Schiit proudly promote the Bifrost as “the world’s most affordable fully upgradable DAC”, with a modular design that allows its existing D/A converter, USB and analogue boards to be swapped out for new ones if and when improvements come on-stream. Such a commitment to effectively future-proof their product in this way is a bold demonstration of both the team‘s long-term belief in the Bifrost and intention to offer continued support to its customers. It is a refreshing antidote to the throwaway society we currently inhabit, in which more and more of the digital audio technology we buy into becomes ‘yesterday’s news’ with ever increasing rapidity.

True to its word, the Uber analogue and asynchronous USB boards can indeed be added to the standard model at a later date. Bifrost owners in need of these additions can return their DAC to Schiit (or Electromod) and have the boards professionally installed at a cost of £60 (Uber) and £80 (USB). Opting for a Bifrost with USB capability from the off is a ‘no-brainer’ in my opinion especially if you are a Mac user, as this permits access to the full gamut of resolutions from 16-bit/44.1kHz through to a theoretical maximum 32-bit/192kHz, and without the mechanical ‘click’ of the Toslink muting relay that some may find objectionable. (For many years Mac OS architecture has restricted Toslink PCM output to a maximum of 96kHz, although apparently the newest Macs now pass up to 192kHz over optical.) The Bifrost is equally at home with Windows based PCs of course but these will require a driver to stream sample rates above 96kHz.A few early bird Bifrost owners (including myself) reported issues with the ‘first generation’ USB board - which used a CM6631 receiver chip - that intermittently manifested as robotic sounding distortion. A ‘second generation’ USB board - deploying a CM6631A chip with additional regulation and filtering - was promptly released to rectify this, and all new Bifrosts and Bifrost Ubers have sported this redesigned interface for some time. The new board also added native support for the 176.4kHz sampling rate. According to its designers it also measures and sounds even better than the previous incarnation, an observation shared by many Bifrost owners (myself included).

The majority of my music collection is still standard 16-bit/44.1kHz PCM in the form of ‘red book’ CD rips, although my library of high-resolution material is growing steadily. I’m not one who has the patience or inclination to experiment with the minutia of software versus hardware upsampling or integer versus non-integer resampling; I prefer to leave that to the ‘golden-eared’ cognoscenti. I simply instruct my software to play all of my material at its respective native sample rate, which the Bifrost’s bit-perfect clock management system delivers to its D/A converter without sample rate conversion, thereby preserving the integrity of the original music samples. Schiit’s meticulous implementation of such a design will not go unnoticed by the ‘bit-perfect puritans’ as SRC-free (sample rate conversion) DACs are few and far between, especially at this price point.

Hot SchiitThe courageous decision to use a bit-perfect clock management system appears to have paid off, as the quality of playback through the Bifrost is extremely impressive regardless of the bit depth and sample rate of the source material. There is no obvious sonic penalty when using lower resolutions. In fact - assuming a high quality mastering - the DAC’s handling of redbook is so good that you may well question the need for higher resolution material, although that is a debate for another arena. Likewise, all three inputs are extremely well implemented and - using a variety of source material resolutions - no audible differences were detected when switching between them. All three were indistinguishable in terms tonal neutrality, level of detail and spatial presentation. This will be welcome news to those who intend to use the asynchronous USB input, as this interface has long been considered as inferior to Toslink optical and S/PDIF coaxial (I’d beg to differ, Ed).

Like many Schiit owners, I found that the Bifrost in standard form requires a substantial period of ‘run-in’ before it reaches peak potential. Out of the box it sounded very different from the Bifrost I’d had on home trial and grown affectionate toward. It was a particularly one-dimensional listen, and a fatiguing one at that. The stereo image lacked width and separation, and the soundstage was short on depth and sounded like the space between instrument layers had been crushed. Tonally the highs were very splashy and presented with an unnerving and accentuated brittleness. Mids were recessed into the soundstage; vocals, piano and guitar sounded distant and lacked presence. Lows appeared congested, ill-defined and had poor placement. Over a two-week period (equating to roughly 300 hours of being powered and having an input signal), the DAC became a more organic and engaging listen as its sonic signature converged with that of the demonstration unit. Stereo width and separation expanded to the point that a realistic soundstage could be envisaged and into which individual instruments could be more accurately placed. The presentation became more dynamic and three-dimensional with an increase in depth and sense of space around instruments, and also improved projection into the listening space. Tonally the highs - whilst still crisp - settled down and lost much of the ‘digital hash’ that had been smearing transient attack and reverb tails. Mids opened up nicely and came to the foreground with vocals, piano and guitar having greater presence and intelligibility. Lows were unshackled and displayed improved ebb and flow and spatial placement.

In stark contrast to my experience with the standard Bifrost, the Bifrost Uber required no ‘run-in’ period. Real-time switching between it and the Uber demonstration unit confirmed an exact sonic match straight from the box, and its sound did not audibly change during subsequent days and weeks of use. I was pleasantly surprised to detect appreciable differences when comparing the Uber with the standard model; the most notable being an improvement in clarity and transparency. Listening through the Uber was as if a fine film of grime had been removed from the soundscape, permitting the listener to hear deeper into the recording and resolve nuances and cues that were previously obscured. There was also a perceptible expansion in soundstage width and depth, with more space being afforded to individual instruments. Layers now floated on more distinct planes, which created an improved three-dimensional image and performance tangibility. Tonally, the Uber offered greater clarity and presence across all frequencies - particularly the mids - and this also helped make the performer-listener relationship more intimate. It was now possible to suspend one’s disbelief and place the musicians right there in the room. This was especially so for vocalists, who were reproduced with a crystalline purity realism that evoked a more profound emotional response. Highs were more refined with less digital grain and displayed more resolving transients and longer reverb tails, both of which were rendered with improved precision and air. Lows were clearer, tighter and more visceral, and reproduced with better placement in the soundstage.

VerdictThe Bifrost and Bifrost Uber are excellent DACs and both represent seriously good value for money. Both are equipped with state-of-the-art technology and will continue to be supported going forward. Which one you should choose will ultimately depend on your budget and preferences for sonic transparency. If you are limited on funds and/or enjoy a richer sound that is delivered with a mild and forgiving haze in which the delicacies of detail and intimacy take a back seat, then the standard Bifrost will more than likely delight. If on the other hand you crave a more open and revealing presentation delivered with refined finesse and a closer emotional connection to your music, then go for the Uber and don’t look back.